This application claims foreign priority of GB 9705739.2 titled Aug. 28, 1997, and GB 970579.2 titled Mar. 20, 1997.
The present invention relates to hemicellulosic cereal extracts suitable as substrates for oxidative gelation (xe2x80x9cgelling hemicellulosesxe2x80x9d), to gels prepared therefrom, to processes for their production, to products containing such gels and to various applications thereof. In particular, the present invention relates to an improved process for preparing gelling hemicelluloses from cereals (especially wheat).
The term xe2x80x9chemicellulosexe2x80x9d and xe2x80x9chemicellulosic material xe2x80x9d are terms of art used to embrace non-cellulosic, non-starch plant polysaccharides. The term therefore embraces inter alia pentosans, pectins and gums.
Some hemicelluloses are suitable as substrates for oxidative gelation (xe2x80x9cgelling hemicellulosesxe2x80x9d): such hemicelluloses often have substituents with phenolic groups which are cross-linkable with certain oxidizing agents.
Arabinoxylan and pectin constitute two particularly important classes of hemicellulose. Arabinoxylans consist predominantly of the pentoses arabinose and xylose, and are therefore often classified as pentosans. However, in many cases hexoses and hexuronic acid are present as minor constituents, and therefore they may also be referred to descriptively as heteroxylans.
The arabinoxylan molecule consists of a linear backbone of (1-4(-xcex2-xylopyranosyl units, to which substituents are attached through 02 and 03 atoms of the xlosyl residues. The major substituents are single xcex1-L-arabinofuranosyl residues. Single xcex1-D-glucoronopyranosyl residues and their 4-O-methyl ethers are also common substituents.
Arabinoxylan preparations are usually heterogeneous with respect to the ratio of xylose to arabinose (i.e. the degree of substitution) and in the pattern of substitution of the arabinosyl units along the (1-4)-xcex2- xylan backbone.
Phenolic acid including ferulic acid) and acetyl substituents occur at intervals along the arabinoxylan chains. These substituents to some extent determine the solubility of the arabinoxylan. Arabinoxylan preparations bearing phenolic (e.g. ferulic acid substituents) are referred to herein as xe2x80x9cAXExe2x80x9d, while those bearing acetyl substituents are designated xe2x80x9cAXAxe2x80x9d. Similarly, preparation bearing both phenolic (e.g. ferulic acid, and acetyl substituents are hereinafter abbreviated to the designation xe2x80x9cAXFAxe2x80x9d. Arabinoxylan preparations having few phenolic (e.g. ferulic acid, substituents are designated xe2x80x9cAXxe2x80x9d: when the degree of substitution falls below that required for oxidative gelation, the arabinoxylan is designated a xe2x80x9cnon-gelling arabinoxylanxe2x80x9d (a term which therefore embraces AX and AXA).
Pectins constitute another important class of hemicelluloses. As used herein and unless otherwise indicated, the term xe2x80x9cpectinxe2x80x9d is used sensu lato to define hemicellulose polymers rich in D-galacturonic acid. Many (but not all) are cell wall components. The term xe2x80x9cpectinxe2x80x9d is also used herein sensu stricto to define the so-called xe2x80x9ctrue pectinsxe2x80x9d, which are characterized by the presence of an O-(xcex1-D-galacturonopyranosyl)-(1-2)-L-rhamnopyranosyl linkage within the molecule.
The pectins may be subcatergorized on the basis of their structural complexity. At one extreme are xe2x80x9csimple pectinsxe2x80x9d, which are galacturonans. At the other extreme are xe2x80x9ccomplex pectinsxe2x80x9d exemplified by rhamnogalacturonan II, which contains at least 10 different monosaccharide components in the main chain or as a components of branches. Pectins of intermediate complexity (herein referred to as xe2x80x9cmesocomplex pectinsxe2x80x9d contain alternate rhamnose and galacturonic acid units, while others have branches of glucoronic acid linked to galacturnoic acid.
Complex and mesocomplex pectins are made up of xe2x80x9csmoothxe2x80x9d regions (based on linear homogalacturonan) and xe2x80x9chairyxe2x80x9d regions corresponding to the rhamnogalacturonan backbone with side-branches of varying length.
Certain pectins (for example, pectins obtainable from representatives of the plant family Chenopodiaceae, which include beets (e.g. sugar beet), spinach and mangelwurzels) are substituted to some extent with substituents derived from carboxylic acids (usually substituted cinnamic acids) containing phenolic groups. Such pectins may be oxidatively cross-linked to produce viscous solutions or gels via their phenolic substituents. This can be achieved by powerful oxidants (e.g. persulfate - see J. - F. Thibault et alia, in The Chemistry and Technology of Pectin, Academic Press 1991, Chapter 7, pages 119-133) or a combination of peroxidase and hydrogen peroxide (see Thibault et alia, ibidem). Fr 2 545 101 Al also describes the gelling of beet pectins using an oxidant (e.g. hydrogen peroxide) and an enzyme (peroxidase). Such pectins are referred to herein as xe2x80x9cgelling pectinsxe2x80x9d.
Sugar beet pectin is especially rich in arabinan. Arabinan contains xcex2-1,5-linked arabinose in the backbone with xcex1-(1- greater than 3) or xcex1-(1- greater than 2)-linked arabinose residues, whereas arabinogalactan contains xcex2-1,4-linked galactose in the backbone, with xcex1-(1- greater than 3) or a xcex1-(1- greater than 2) linked arabinose residues. Ferulyl substituents are linked to the arabinose and/or the galactose in the arabinan and arabinogalactan side-branches of the rhamnogalacturonan part. The xe2x80x9cferulic acidxe2x80x9d content varies according to the extraction method, but is often about 0.6%.
Beet pectins obtained by processes which partially remove arabinose residues may exhibit improved gelling properties. Thus, procedures involving mild acid treatment and/or treatment with an xcex1-arabinofuranosidase will improve the gelling properties of the pectin (see F. Guillon et alia ibidem). Such pectins are hereinafter referred to as xe2x80x9ctreated pectinsxe2x80x9d.
It has long been known that certain flour extracts (e.g. wheat and rye flour extracts) can form gels in the presence of certain oxidants (e.g. upon the addition of hydrogen peroxide). The phenomenon is known in the art as xe2x80x9coxidative gelationxe2x80x9d, and an extensive literature exists on the subject of oxidative gelation of wheat flour extracts. According to the literature, the gels arise as high molecular weight arabinoxylan and protein molecules become inter- and/or intra-linked (via inter alia diferulate bridges) - see e.g. Hoseney and Fabuion (1981), Cereal Chem., 58: 421.
Most of the work in this area has focused on water soluble pentosans from wheat flour. In these studies, wheat flour is extracted with water (usually at room temperature) to yield gelling arabinoxylans. However, water-insoluble wheat pentosans extracted from wheat flours with various concentrations of cold sodium hydroxide have also been shown to form gels (Michniewicz et alia, Cereal Chemistry 67(5): 434-439 (1990).
WO 93/1058 describes the preparation of hemicellulosic material from various brans and the oxidative gelation of maize-derived hemicelluloses using an oxidizing system comprising a peroxide, (such as hydrogen peroxide) and an oxygenase (such as a peroxidase). The hemicellulosic material for use as a gelling agent is prepared by hot water or mild alkali extraction.
However, gelling hemicelluloses from some cereal sources (including wheat) produced by known processes form gels which are unsatisfactory for many uses. Such gels are generally opaque, relatively soft, pigmented and exhibit marked syneresis on storage. These properties limit their utility in many potential fields of application (including food technology and the pharmaceutical industry).
There is therefore a need for improved methods of producing gelling hemicelluloses from testaceous cereal fractions (e.g. cereal brans) which exhibit improved gelling characteristics and which do not exhibit these undesirable properties.
It has now been discovered that the undesirable characteristics of the gels produced from certain hemicellulosic bran extracts arise from the presence of contaminating proteins. In certain brans (e.g. many what brans and other bran sources which contain residual endosperm material), such proteins are present at concentrations sufficient to impair or prevent the gelation (or to impair the physical properties of the resultant gels. The present inventors have found that substantially reducing the amount of contaminating proteins in the hemicellulosic material prior to gelation makes possible the production of gelling hemicellulose from a wider range of bran sources (including those previously thought as intractable or unsuitable as starting materials) than has hitherto been possible, and significantly improves the quality of the resultant gels.
This novel finding is particularly surprising in the light of the critical role thought to be played by proteins in the gelling process (see e.g. Hoseney and Fabuion (1981), Cereal Chem., 58: 421, referred to infra).
Thus, according to the present invention there is provided a process for the production of a gelling hemicellulose from a bran containing interfering levels of contaminating protein, the process comprising the steps of extracting hemicellulose from the bran and removing the contaminating protein before and/or after extraction.
As used herein, the term xe2x80x9cinterfering levels of contaminating proteinxe2x80x9d refers to concentrations of bran-associated proteins which are sufficient to impair the quality of gels produced by oxidative gelation of hemicellulose extracts prepared therefrom (or prevent or impair gelation of such hemicellulose extracts). In general, protein concentrations of 10% w/w or greater (with respect to the total weight of the bran starting material) are at interfacing levels (within the terms of the definition set out above). The contaminating protein is usually endogenous to the bran (i.e. carried over from the milling process), and often comprises or consists of endosperm material. Examples of brans which contain interfering levels of contaminating proteins include many wheat brans and some European corn brans. In many cases, brans which contain interfering levels of contaminating proteins are those which are associated with significant amounts of residual endosperm material.
The contaminating protein need not be removed entirely, but merely to a level sufficient to improve the gelling characteristics or gel quality of the gels ultimately produced. The level of contaminating protein is preferably reduced to a level sufficient to restore or improve the gel (or extract gelling) properties. For example, the contaminating protein concentration may be reduced to below about 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%.
The contaminating protein may be removed from the bran by any convenient method, and a wide variety of suitable techniques are known to those skilled in the art. The protein may be removed from the bran itself prior to extraction, from the hemicellulosic bran extract, or from both.
Conveniently, protein removal may include classifying, washing and/or sieving the bran. In such processes, contaminating starch may be removed together with the contaminating protein. In such (dry) techniques, contaminating protein may be removed from the bran as endosperm fragments on the basis of size (e.g. by air classifying, washing or sieving the bran). Preferably, the bran is sieved through a mesh of 0-250 xcexcm, 250-260 xcexcm, 600-1000 xcexcm and/or grater than 1000 xcexcm. The sieving may be followed by air classification of the sieved bran to remove endosperm fragments, e.g. through a mesh of less than 600 xcexcm (e.g. less than 250 xcexcm. Alternatively, or in addition, contaminating protein may be removed from the bran by washing, for example with hot water or acid (e.g. at a pH of 3-6, e.g. about 5).
Contaminating protein may also be removed from the bran and/or the hemicellulose extract by treatment with a protease. This technique can be applied as the sole protein removal step, or used in any combination with any other method, such as those disclosed herein. In such embodiments, a bran residue may be recovered from protease treatment and the residue washed with hot water or acid (e.g. at a pH of 3-6, e.g. about 5). The protease treatment is conducted for a period of time sufficient to improve the gelling characteristics and/or ultimate quality of the resultant gels, and for example may be conducted for about 10-20 min (e.g. about 1 hr), for example at 30-80xc2x0 C., (e.g. about 50xc2x0 C.).
Alternatively, or in addition, contaminating protein may be removed from the hemicellulose extract by heat treating the hemicellulose extract to form a proteinaceous precipitate (for example at 70-100xc2x0 C., e.g. about 35-100xc2x0 C., optionally for 5-60 min, e.g. about 20 min). Preferably, such heat treatment comprises the steps heat treating the hemicellulose extract to form a proteinaceous precipitate; removing the precipitate to produce a hemicellulose-enriched supernatant and then recovering gelling hemicellulose from the enriched supernatant.
Other techniques which may be used according to the present invention (alone or in combination with other protein removal steps) include precipitation (e.g. isoelectric precipitation), filtration (e.g. ultrafiltration and/or filtration on vega clay), chromatography (e.g. silica hydrogel and/or ion exchange chromatography) and/or alcohol (e.g. IMS) precipitation, for example with up to 30% v/v alcohol. Particularly preferred is the use of isoelectric precipitation of the hemicellulose extract at a pH of between 2 and 5 (e.g about 4).
In preferred embodiments, the process comprises the steps of: (a) treating the bran with a protease to yield a bran digest (e.g. under the conditions defined above); (b) extracting hemicellulose from the digest of step (a); (c) heat treating the hemicellulose extract of step (b) to form a proteinaceous precipitate; (d) removing the precipitate of step (c) to produce a hemicellulose-enriched supernatant; (e) recovering gelling hemicellulose from the enriched supernatant of step (d). The bran residue may be recovered after protease treatment and the residue washed with hot water or acid (e.g. at a pH of 3-6, e.g. about 5).
Preferably, the hemicellulose extraction is an alkaline extraction, for example a mild alkaline extraction. For example, the alkaline extraction may be carried out under conditions which do not substantially deferulate polysaccharides (e.g. arabinoxylan) in the hemicellulose. Particularly preferred are alkali extractions conducted with alkali metal hydroxides, such as sodium hydroxide, calcium hydroxide and potassium hydroxide. Calcium hydroxide is particularly advantageous where clear gels are required, because it can be readily precipitated out. The hydroxide is preferably used at about 1-15%, though the optimum amount can be readily determined by routine trial and error by those skilled in the art and depends inter alia on the particular bran source used. For example, concentrations of about 5% are useful for many wheat brans, whereas concentrations of about 10% are preferred for maize brans. Particularly preferred for wheat brans is potassium hydroxide at about 54 w/w. The alkaline treatment is preferably carried out for about 10-120 min, for example for about 1 hr. The extraction may be conducted at 30-80xc2x0 C. (e.g about 60xc2x0 C.).
Preferably, the process further comprises the step of recovering gelling hemicellulose by alcohol precipitation, optionally followed by drying.
A particularly preferred process is shown in schematic form in FIG. 1. Here, xe2x80x9cBWBxe2x80x9d and xe2x80x9cFWBxe2x80x9d are abbreviations for broad wheat bran and fine wheat bran, respectively. The xe2x80x9cWIPxe2x80x9d and xe2x80x9cWSPxe2x80x9d processes are abbreviations for the water insoluble and water soluble pentosan co-product process respectively. The arrow to the protein deposit shown (xe2x80x9cPDxe2x80x9d) is another important co-product route. The process shown in this figure may further comprise xe2x80x9cfine finishingxe2x80x9d steps after final trituration in IMS. Such fine finishing may include, for example, starch removal (e.g. by processes comprising centrifugation).
The gelling hemicellulose may comprise a pentosan, e.g. a water soluble or alkali soluble pentosan fraction. Particularly preferred is arabinoxylan, for example arabinoxylan ferulate. For many applications, the gelling hemicellulose will consist of (or consist essentially of) arabinoxylan ferulate.
The bran may be any bran in which the level of contaminating protein is sufficiently high so as to interfere with oxidative gelation of hemicellulose extracts prepared therefrom (e.g. by alkaline extraction as described, for example, infra). The brain is preferably a cereal bran, for example European corn bran (e.g. German corn bran) or wheat bran.
In another aspect, the invention contemplates a process for the production of a hemicellulose gel comprising the steps of: (a) preparing a gelling hemicellulose according to a process as defined in any one of claims 1-28; and then (b) oxidatively gelling the hemicellulose obtained in step (a) to yield a hemicellulose gel.
The processes of the invention yield useful and important co-products. These include bran derived starch, protein, starch-protein mixtures and the unextracted residue left after extraction of the gelling hemicelluloses. This latter material can be further processed (as described infra) to yield a variety of soluble and insoluble pentosan extracts having a wide range of uses in the food industry, the pharmaceutical industry and more generally (e.g. as adhesives or sealants). The protein produced as a by product of the invention has been found to exhibit excellent organoleptic qualities (particularly when digested to varying extents with a protease). Moreover, it has an excellent amino acid profile and is particularly nutritious, being superior to gluten in many respects. Without wishing to be bound by any theory, it is thought that the protein co-products of the invention comprise non-storage protein derived from the endosperm of the plant from which the bran was produced.
Thus, the processes of the invention preferably further comprise the step of recovering the contaminating protein removed from the bran (e.g. in digested form), and may also further comprise the step of recovering contaminating starch removed from the bran (e.g. in admixture with the contaminating protein).
In another aspect, the invention relates to a process for preparing a protein or a mixture of starch and protein comprising the steps of: (a) providing a bran (for example a bran as defined in claim 28); (b) removing protein (and optionally starch) from the bran by processing as defined in any one of claims 1-28; and (c) recovering the protein (optionally in admixture with starch) removed in step (b); and optionally (d) drying or concentrating the protein (and optionally the starch) recovered in step (c).
The invention also contemplates various products comprising the co-products of the invention. Such co-products may, for example, be formulated as a food, food ingredient, food base, food additive or functional feed ingredient comprising the protein co-product of the invention.
The protein co-product may be formulated as: (a) an emulsifier; (b) a binder; (c) a whipping agent; (d) a soya analogue; (e) a milk analogue; (f) a protein isolate or concentrate; (g) a flavouring agent; (h) a dehydrated beverage; (i) a roux or roux blanc; (j) a moisture barrier. For some applications, it is preferred that the protein co-product be at least partially digested, conveniently by the protease treatment applied to the bran or hemicellulose extract in the main product pathway.
The gelling hemicellulose may conveniently be provided in the form of a powder, for example a substantially anhydrous power and optionally a dispersant (e.g. glucose or maltodextrin). In this form it may further comprise an oxidase, oxidase substrate (e.g. glucose) and optionally peroxidase supplements, so that the material is self-gelling on the addition of water.
The gelling hemicellulose of the invention may also be provided in the form of an aqueous solution, which is advantageously substantially oxygen free. Such materials may also comprise an oxidase, oxidase substrate (e.g. glucose) and optionally peroxidase supplements, and so also be self-gelling on exposure to oxygen.
The invention also contemplates a gel or viscous medium comprising the gelling hemicellulose of the invention which has been oxidatively gelled. The gelling hemicellulose may comprise (or consist of) cross linked arabinoxylan.
The invention also contemplates a pharmaceutical or cosmetic preparation or medical device comprising the hemicellulosic materials of the invention. The preparation or device may for example be selected from: a wound plug, wound dressing, wound debriding system, controlled release device, an encapsulated medicament or drug, a lotion, cream, suppository, pessary, spray, artificial skin, protective membrane, a neutraceutical, prosthetic, orthopaedic, ocular insert, injectant, lubricant or cell implant matrix. In such embodiments the material, gel or viscous medium of the invention may further comprising an antibiotic, electrolyte, cell, tissue, cell extract, pigment, dye, radioisotope, label, imaging agent, enzyme, co-factor, hormone, cytokine, vaccine, growth factor, protein (e.g. a therapeutic protein), allergen, hapten or antigen (for e.g. sensitivity testing), antibody, oil analgesic and/or antiinflammatory agent (e.g. NSAID).
The invention also covers the materials of the invention for use in therapy, surgery, prophylaxis or diagnosis, for example in the treatment of surface (e.g. skin or membrane lesions, e.g. burns, abrasions or ulcers).
In a particularly preferred embodiment, the invention contemplates a wound dressing comprising the material of the invention, for example in the form of a spray. Such would dressings are particularly useful for the treatment of burns, where their great moisture retaining properties help to prevent the wound drying out. Particularly preferred for such application is the self-gelling liquid of the invention which gels on contact with oxygen in the air. Such compositions can be provided in the form of oxygen-free liquids in airtight containers which can be sprayed onto the skin, whereupon the liquid gels after exposure to the air. Such composition may advantageously be formulated so as to produce a slight excess of hydrogen peroxide on exposure to oxygen, so that a sterilizing, antibacterial, bacteriostatic and/or cleansing effect is obtained which helps promote healing.
The invention also contemplates water absorbant nappies, diapers, incontinence pads, sanitary towels, tampons and panty liners comprising the materials and gels of the invention, as well as domestic and industrial cleaning or liquid (e.g. water) recovery operations (e.g. in the oil industry).
Alternatively, the gels of the invention can be provided in the form of hydrated or dehydrated sheets or pellicles for application to various internal or external surfaces of the body, for example during abdominal surgery to prevent adhesions. Other embodiments include enzyme immobilizing systems and brewing adjuncts. Also contemplated is a bread improver comprising the material, gel or viscous medium of the invention.
The invention also covers a foodstuff, dietary fibre source, food ingredient, additive, lubricant, supplement or food dressing comprising the material, gel or viscous medium of the invention. Such products are preferably selected from crumb, alginate replacer, cottage cheeses, aerosol toppings, frozen yoghurts, milk shakes, ice cream, low calorie products such as dressings and jellies, batters, cake mixes, frozen chips, binders, gravies, pastas, noodles, doughs, pizza toppings, sauces, mayonnaise, jam, preserve, pickles, relish, fruit drinks, syrups, toppings and confectionary (e.g. soft centres), petfood (wherein the gel e.g. acts as a binder), a flavour delivery agent, a canning gel, fat replacer (e.g. comprising macerated gel of any one of claims ), a coating, a glaze, a bait, a binder in meat and meat analogue products (for example vegetarian products), a gelatin replacer or dairy product or ingredient (e.g. a yoghurt supplement). When used as a fat replacer the gel of the invention is preferably macerated to optimize its mouthfeel and fat mimetic properties.
The invention also finds application in the extraction of gelling hemicelluloses from sources other than bran which may contain interfering levels of contaminating protein. The invention may be used to extract essentially any hemicellulose (within the definition set out earlier). In particular, the hemicellulose may be an arabinoxylan, heteroxylan or pectin. In addition, the hemicellulose for use in the processes of the invention may be a synthetic hemicellulose (i.e. a structural analogue of a naturally-occurring hemicellulose synthesized in vitro by any chemical/enzyme synthesis or modification). Arabinoxylans, heteroxylans and pectins may also be used. Of the arabinoxylans, particularly preferred are AXFA, AXF, AXA and AX.
Also suitable for use in the invention are pectins, including the true pectins, simple pectins, complex pectins, mesocomplex pectins and gelling pectins (e.g those obtainable from representatives of the plant family Chenopodiaceae, which include beets, (e.g. sugar beet), spinach and mangelwurrels). Particularly preferred is sugar beet pectin (for example in the form of sugar beet pulp). Also useful in the invention are treated pectins (as hereinbefore defined).
Examples of sources other than bran which may be used as starting materials according to the invention include any non-cellulosic, non-starch plant polysaccharides. Thus, the processes of the invention find application in the processing inter alia of pentosans, pectins and gums. Suitable starting materials containing hemicellulose for use in the processes of the invention typically include plant material of various kinds and any part or component thereof.
Plant materials useful as a starting material in the invention include the leaves and stalks of woody and nonwoody plants (particularly monocotyledonous plants), and grassy species of the family Gramineae. Particularly preferred are gramineous agricultural residues, i.e. the portions of grain-bearing grassy plants which remain after harvesting the seed. Such residues include straws (e.g. wheat, oat, rice, barley, rye, buckwheat and flax straws), corn stalks, corn cobs and corn husks.
Other suitable starting materials include grasses, such as prairie grasses, gamagrass and foxtail. Other suitable sources include dicotyledonous plants such as woody dicots (e.g. trees and shrubs) as well as leguminous plants.
Another preferred source are fruits, roots and tubers (used herein in the botanical sense). The term xe2x80x9cfruitxe2x80x9d includes the ripened plant ovary (or group thereof) containing the seeds, together with any adjacent parts that may be refused with it at maturity. The term xe2x80x9cfruitxe2x80x9d also embraces simple dry fruits (follicles, legumes, capsules, achenes, grains, samaras and nuts (including chestnuts, water chestnuts, horsechestnuts etc.)), simple fleshy fruits (berries, drupes, false berries and pomes), aggregate fruits and multiple fruits. The term xe2x80x9cfruitxe2x80x9d is also intended to embrace any residual or modified leaf and flower parts which contain or are attached to the fruit (such as a bract). Encompassed within this meaning of fruit are cereal grains and other seeds. Also contemplated for use as starting material are fruit components, including bran, seed hulls and culms, including malt culms. xe2x80x9cBranxe2x80x9d is a component of cereals and is defined as a fraction obtained during the processing of cereal grain seeds and comprises the lignocellulosic seed coat as separate from the flour or meal. Other suitable component parts suitable as starting materials include flours and meals (particularly cereal flours and meals, and including nonwoody seed hulls, such as the bracts of oats and rice).
The term xe2x80x9crootxe2x80x9d is intended to define the usually underground portion of a plant body that functions as an organ of absorption, aeration and/or food storage or as a means of anchorage or support. It differs from the stem in lacking nodes, buds and leaves. The term xe2x80x9ctuberxe2x80x9d is defined as a much enlarged portion of subterranian stem (stolon) provided with buds on the sides and tips.
Preferred lignocellulosic starting materials include waste stream components from commercial processing of crop materials such as various beets and pulps thereof (including sugar beet pulp), citrus fruit pulp, wood pulp, fruit rinds, nonwoody seed hulls and cereal bran. Suitable cereal sources include maize, barley, wheat, oats, rice, other sources include pulses (e.g. soya), legumes and fruit.
Other suitable starting materials include pollen, bark, wood shavings, aquatic plants, marine plants (including algae), exudates, cultured tissue, synthetic gums, pectins and mucilages.
Particularly preferred as a starting material is testaceous plant material, for example waste testaceous plant material (preferably containing at least about 20% of arabinoxylan and/or glucoronoarabinoxylan).
The starting material may be treated directly in its field-harvested state or (more usually) subject to some form of pre-processing. Typical pre-processing steps include chopping, grinding, cleaning, washing, screening, sieving etc.
The hemicellulose products (i.e. the gels, dehydrated gels, rehydrated dehydrated gels, non-gelling hemicelluloses, gelling (but ungelled) hemicelluloses and viscous liquids of the invention find a variety of applications various therapeutic, surgical, prophylactic, diagnostic and cosmetic (e.g. skin care) applications.
For example, the aforementioned materials may be formulated as a pharmaceutical or cosmetic preparation or medical device, for example selected from: a wound plug, wound dressing, wound debriding system, controlled release device, an encapsulated medicament or drug, a lotion, cream (e.g. face cream), suppository, pessary, spray, artificial skin, protective membrane, a neutraceutical, prosthetic, orthopaedic, ocular insert, injectant, lubricant or cell implant matrix. The non-gelling gelling and gelled hemicelluloses (e.g AX, AXF and gelled AXF) are particularly useful as agents which maintain the integrity of the gut wall lining, and as agents for coating the luminal wall of the gastrointestinal tract. They may therefore fins particular application in animal feeds and in the treatment of gastrointestinal disorders.
In such embodiments the material, gel or viscous medium of the invention may further comprising an antibiotic, electrolyte, cell, tissue, cell extract, pigment, dye, radioisotope, label, imaging agent, enzyme co-factor, hormone, cytokine, vaccine, growth factor, protein (e.g. a therapeutic protein), allergen, hapten or antigen (for e.g. sensitivity testing), antibody oil, analgesic and/or antiinflammatory agent (e.g. NSAID).
Thus, the above-listed materials find application in therapy, surgery, prophylaxis or diagnosis, for example in the treatment of surface (e.g. skin or membrane lesions, e.g. burns, abrasions or ulcers). In a particularly preferred embodiment, the invention contemplates a wound dressing comprising the above listed materials of the invention, for example in the form of a spray. Such wound dressings are particularly useful for the treatment of burns, where their great moisture retaining properties help to prevent the wound drying out.
Particularly preferred for such application is a self-gelling liquid comprising gelling hemicellulose supplemented with glucose and peroxidase and/or oxidase enzymes which gels on contact with oxygen in the air. Such compositions can be provided in the form of oxygen-free liquids in airtight containers which can be sprayed onto the skin, whereupon the liquid gels after exposure to the air. Such composition may advantageously be formulated so as to produce a slight excess of hydrogen peroxide on exposure to oxygen, so that a sterilizing, antibacterial, bacteriostatic and/or cleaning effect is obtained which helps promote healing.
The invention also contemplates water absorbent nappies, diapers, incontinence pads, sanitary towels, tampons and panty liners comprising the above-listed materials, as well as domestic and industrial cleaning or liquid (e.g. water) recovery operations (e.g. in the oil industry).
Alternatively, the gels of the invention can be provided in the form of hydrated or dehydrated sheets or pellicles for application to various internal or external surfaces of the body, for example during abdominal surgery to prevent adhesions.
Other applications include enzyme immobilizing systems, brewing adjuncts and bread improvers.
The materials listed above also find application as a foodstuff, dietary fibre source, food ingredient, additive, lubricant, supplement or food dressing. Such products are preferably selected from crumb, alginate replacer, cottage cheeses, aerosol toppings, frozen yoghurts, milk shakes, ice cream, low calorie products such as dressings and jellies, batters, cake mixes, frozen chips, binders, gravies, pastas, noodles, doughs, pizza toppings, sauces, mayonnaise, jam, preserve, pickles, relish, fruit drinks, a clouding agent in drinks, syrups, toppings and confectionary (e.g soft centres), petfood (wherein the gel e.g. acts as a binder), a flavour delivery agent, a canning gel, fat replacer (e.g. comprising macerated gel), a coating, a glaze, a bait, a binder in meat and meat analogue products (for example vegetarian products), an edible adhesive, a gelatin replacer or dairy product or ingredient (e.g. a yoghurt supplement).
When used as a fat replacer the gel of the invention is preferably macerated to optimize its mouthfeel and fat mimetic properties.
The ungelled gellable hemicelluloses and the non-gelling hemicelluloses find particular utility as biodegradable gums and adhesives, e.g for use in the paper and packaging industries.
Nongelling hemicelluloses (for example, AX) also find particular application as stabilizers, thickeners and gelatin replacers. They have excellent mouthfeel and texture when used in, for example, mousses and other dairy products.
The ungelled (but gellable) hemicelluloses (e.g. AXF) find particular application as clouding agents (e.g in drinks), as film forming agents (e.g. in moisture barriers), glazes, edible adhesives and other functional food ingredients.
The cellulose fibre is usually bleached prior to use. It has high water holding capacity, and dispersions may be sheared to produce highly viscous pastes. Particularly preferred applications for this (co) products include dressings (e.g as a modified starch replacer), yogurts and coatings (and especially batters), where it may act as a crisping agent.
The protein (co) products of the invention have been found to exhibit excellent organoleptic qualities (particularly when digested to varying extents with a protease). Moreover, they have an excellent amino acid profile and are particularly nutritious, being superior to gluten in many respects. Without wishing to be bound by any theory, it is thought that the protein (co) products of the invention derived from starting materials comprising bran comprise non-storage protein derived from the endosperm of the plant from which the bran was produced.
The protein co-product may be formulated as: (a) a emulsifier; (b) a binder; (c) a whipping agent; (d) a soya analogue; (e) a milk analogue; (f) a protein isolate or concentrate; (g) a flavouring agent; (h) a dehydrated beverage; (i) a roux or roux blanc; (j) a moisture barrier.
For some applications, it is preferred that the protein co-product be at least partially digested, conveniently by the protease treatment applied to the starting material (e.g. bran) or hemicellulose extract in the main process stream.
The various other co-products of the invention (including the xcex2-glucan, starch, protein, cellulose, phenolic extracts, lignin, wax, cutin and/or suberin) find application as foods, food ingredients, food bases, food additives or functional food ingredients. They also find application in various forms of therapy (particularly wound healing).
Particularly preferred in the latter respect are the phenolic extracts of the invention, which also find particular utility as flavouring agents (e.g vanilla flavourings).
Some of the phenolic extracts and/or waxes, cutins and/or suberins find particular utility as pesticides or crop protection agents.